Device fob indicating oscillograph



Dec. 13, 1938. F, BEDELL Re. 20,945

DEVICE FOR INDICATlNG OSCILLOGRAPH CURVES As STATIQNARY Original Filed May 7, 1927 ,2 Sheets-Sheet l 5oz/Ice; afcwfenl ar Mii vvvv

aNvENToR BY BEfZ ATTO R N EYS Dec. 13, 1938. Fl BEDELL Re. 20,945

DEVICE FOR I-NDICATING OSCILLOGRAPH CURVES AS STATIONARY 65 INVENTQR ATTQRNEYS IReissued Dec. 13, 1938 UNITED STATES PATENT OFFICE DEVICE Fon mmcA'rlNo osolLnoGArn CURVES AS STATIONARY Original No. 1,707,594, dated April 2, 1929, Serial No. 189,727, May 7, 1927. Application for reissue August 18, 1937,

13 Claims.

My invention relates to improvements in devices for indicating oscillograph curves as stationary, and it consists in the combinations, conf structions, and arrangements herein described and claimed. f

Devices for showing oscillograph curves, such as produced by a cathode ray impinging on a fluorescent screen, have been used, whereby variations in electrical quantities such as voltages or currents may be observed. In such devices, however, the resulting curves or waves representing the varying quantities -are apt to be confused.

An object of my invention is to provide a. device, by means of which such curves are indicated as stationary, thereby increasing materially the utility of the device.

A further object is to provide an arrangement, by means of which several waves or half waves may be centered upon a fluorescent screen or plate, and in which distortion is avoided, so that the shape of the curve practically represents the variations from instant to instant of the quantitles under observation.

A further object is to provide an arrangement for accomplishing the above-named objects in which a cathode-ray tube is made use of with a set of deecting elements which has impressed upon it an electromotive force or current under observation and a second set of elements which has impressed upon it a current orelectromotive force varying substantially in direct proportion to time, so that the resulting deflection of the cathode beam in one direction is proportional to the electrical quantity under observation, and the deflection in the other direction is proportional to time, giving a so-called 1inear" timeaxis.

A further object is to provide a. polycyclic distributor, by means of which several currents or electromotive forces separately in rapid succession may be applied to the irst set of deflecting elements, so that to the eye or photographic plate the several resulting curves, representing the several unknown quantities under observation, although produced separately, appear simultaneous and continuous.

A further object is to provide an assembly of control and supply devices, said control devices consisting of resistors and means for effecting their variations, so that one part of the circuit system may be adjusted Without disturbance to some other part, and of means in association with said resistors, whereby residual fluctuations in the current supply are so compensated that dis- Serial No. 159,732

turbing variations in the intensity of the cathode beam are avoided.

Other objects and advantages will appear in the following specification, and the novel features of the invention will be particularly pointed out 5 in the appended claims.

My invention is illustrated in the accompanying drawings, forming part of this application, in which Figure 1 is a diagrammatical view, showing the arrangement of the electrical circuits, of one form of the invention,

Figure 2 is a view showing the relation of the screen to the deector plates of Figure 1,

Figure 3 is a modified form of a, portion of the circuit,

Fig. 4 is a diagrammatic view of a modified form of the device, and

Figure 5 is a diagrammatic view showing the development of a polycyclic distributor.

Referring to Figure 1, I have indicated the cathode 6 of a cathode-ray oscillograph tube as a hot ilament', heated by current controlled by the resistance 1, this current being either direct current derived from a battery 8 by means of the conductors 9 and III or by alternating current derived from the secondary winding II of the transformer I2 when the switch S is shifted to the position shown in Figure 1.

The anode is shown at I3 and is maintained at a definite positive potential (hereinafter referred to as the operating potential) with respect to the cathode 6 in a manner described later. This operating potential is less when the cathode is heated, as here shown, but it will be understood that my invention applies to any type of cathode-ray tube and is not limited to a tube employing a hot cathode. The two sets of defiecting elements are indicated at I4, Ida and I5, I5a, respectively. Associated With these elements either within or without the tube is a plate I 6, such as a fluorescent screen, upon which curves I1 are to be observed. The relation of the plate IE and the deilecting elements is shown in Figure 2.

One set of defiecting elements is connected to the electrical circuit or circuits upon which observation is to be made and the other set to a source of electromotive force varying substantially in direct proportion to time. The deflect- 50 ing elements, as here shown, are plates, and it is commonly desirable in this case to connect one plate of each pair or set, as the plates I 4 and I5, to the anode I3.

In Figure 1 I have shown the operating poten- 55 tial which is applied between the cathode 5 and the anode I3 as being derived from certain points on a resistor system to which a uni-directional current is flowing and from other points on the same system to derive the potential difference for operating the oscillating circuit for obtaining the linear time-axis, as described later. The unidirectional current through this resistor system, as shown in Figure 1, is derived by rectiiying and illtering alternating current obtained from the secondary I8 of the transformer I2, the primary I3 of which is connected to a lighting or other source of alternating current. Connected with the secondary I8 of the transformer I2 is a suitable rectifying device 2li. 2|, 22 and 25 are condensers and 23 and 24, choke coils to lter or smooth out the current in the usual manner.

, The coils 23 and 24 possess mutual inductance for added stability. 26 and 21 are impedances, the condenser 25 being connected to these impedances across the lines leading from the choke coils 23'and 24, this arrangement constituting a compensating or ballast device. as described later.

From the terminals of the condenser 25, conductors lead to the points 29 and 3|, respectively, these being the points from which the operating potential for the cathode tube is derived.

The resistor system is generally indicated by the apparatus disposed between the points 25, 23, 3U, 3| and 32. 'Ihe resistance 33 is an equalizing resistance for controlling the potential of the point 3| with respect to the point 34.

At I have indicated diagrammatically a socalled discharge lamp, comprising two electrodes or terminals in a gas-tight vessel containing neon, argon or like gas. As is well known, such a gas-discharge lamp permits no current to flow unless the potential applied to its terminals equals or exceeds a certain so-called ignition voltage. Current will then continue to ow, even with a lower applied voltage, until the voltage falls to or below a certain so-called extinction voltage. In series with the gas-discharge lamp 35 are the resistances 35, 31 and 38. 33 is a condenser which may be used to increase the capacitance of the gas-discharge lamp 35, which itself acts like a condenser with a certain capacitance. In operation, when a potential derived from 32 and 33 is applied to the circuit 35, 35, 31 and 33, no eurrent ows through the lamp until the difference of potential at its terminals has increased approximately in proportion to time, to the ignition voltage. Current then ows and the dierence of potentials almost instantly falls until the extinction voltage is reached. Current then stops ilowing, the potential then again rises and the cyclic process is repeated.

Referring to the upper portion oi *Figure 1. I have shown two sources of current or potential, which I have indicated In general at A and B. These sources of current are connected through transformers a and b to the terminals 40, 42 and 4|, 43, respectively. The source A is also connected by a transiormer a' with the terminals of the resistance 36, variable resistances 44 and 45 being interposed, as shown. The secondary of the transformer a' may have taps 45. In Figure l I'have shown the potential dit# ference between the points 3| and 34 before being applied to the deflecting elements as being amplined. To this end, the grid 41 is connected with the point 34 and the lament 43 receives its current from the conductors 9 and Ill through a resistance 43. Plate voltage is supplied to the plate 53 by an adjustable connection at 5| with the resistor system. In the plate circuit is a resistor 52. When the point 3| is at the proper xed potential, determined by the values of the several parts of the resistor system and controlled by the operator by means of the equalizing resistance 33, as described later; the fall of potential of the plate current through the resistor 52 is proportional to the difference oi potential beween the'points 3| and 34 and may be applied directly to the pair of deecting plates I5 and I5". One terminal of the resistor 52 is connected to the plate I5, while the other terminal is connected to the point 5|, which is adjustable, as

stated.

The resistor system 28, 29, 30, 3| and 32 supplies from two points, as 29 and 3|, the operating potential for the cathode tube, as already explained. It also supplies from two points, as 32 and 30, potential for the oscillating circuit 32, 34, 30, which, through synchronous oscillations in the potential of the point 34, makes it possible to apply to the deflectingeelements I5 and I5n a potential difference varying substantially in direct proportion to time. Not only is there applied to the plates I5 and I5* the fall of potential through 52, varying approximately with time, but also the constant supplemental fall oi potential through a controllable part oi' the resistor, so that the cathode beam may, by varying the amount of this supplemental diilerence of potential, be centered or decentered at will, thereby making possible the use oi.' the same resistor system for supplying the operating potential for the cathode tube as supplies the potential ior the oscillating circuit for obtaining the linear time-axis.

The frequency with which the gas-discharge lamp charges and discharges may be controlled by the variable resistance 38 in series therewith, or by changing the capacitance of the condensers 39. and 39 in parallel, respectively, with the lamp 35 and the variable resistance 33. This frequency may thus be made approximately equal to the frequency of some periodically varying quantity under observation, or to bear some rational ratio (i. e.. a ratio of two whole numbers) thereto. It is necessary, however, to make this relation precise, in order that the wave or gure shown by the variation of the cathode beam stands stationary for observation, in other words, to stabilize the linear time-axis. A feature oir my invention is the means for accomplishing this and for bringing the discharge of the gas tube in precise synchronism with a periodic quantity under observation. I have found that when the discharge of the gas-discharge tube is not precisely synchronous it may be stabilized and brought into precise synchronism by introducing into the oscillating circuit a very small electromotive force derived i'rorn the same source as the periodic quantity under observation. I have found, however, that the introduction of this electromotive force will produce distortion in the resulting wave shown by the oscillograph, unless introduced in such a manner as not to be applied directly or indirectly, either in part or in whole, to the circuit leading to the deilecting plates of the oscillograph.

'Ihe means for effecting this stabilization without distortion are shown in Figure 1. The primary of the transformer a' ls supplied with periodically varying current from the source A that supplies the circuit under observation through the transformer a. The secondary circuit of the transformer a' is connected, as stated, to the terminals 'oi' the resistance 36 in series with the gas-discharge lamp 35.

In operation, when the potential of the gasdischarge lamp 35 has increased to nearly the ignitionvoltage, a tiny impulse from the transformer applied to the terminals of the resistance 36 is sufllcient to cause it to discharge synchronously with the source leading to the transformers a and a. I have found that a very minute amount of energy, thus applied, brings absolute synchronism.

Even a small amount of energy, however, if allowed to affect the deilecting plates of the oscillograph, would cause objectionable distortionv in the resulting wave. By introducing voltage in the manner shown in Figure 1, I have been able to obviate such distortion, making use, for this purpose, of the properties of the gas-discharge lamp itself; for, while the gas-discharge lamp is charging, it allows no current to ilow; stabilizing current flows through the resistance 36 only and none of it gets through the gas-discharge lamp 35 so as to afl'ect the oscillograph. Should any stabilizing current get through during the instant that the gas-discharge lamp discharges, it would be immaterial and produce no distortion, for the wave-form under observation is produced while the gas-discharge lamp 35 is charging. The degree of stabilization may be controlled by the resistances 45 or 44 or by the taps on the transformer a'. 'I'he oscillating circuit is inductively coupled with the source A, the transformer a serving as an insulating transformer for this purpose,

In connection with Figure l, I have previously explained that I employ a illter system for supplying unidirectional current through a resistor system for supplying both the oscillating circuit and the operating potential of the tube. I nd that in order to render these two functions independent, it is desirable to employ a compensating or ballast device to maintain uniform difference of potential between the points 3I and 34 and to eliminate so far as possible the eifect of any residual fiuctuations in the operation of the tube. For this purpose, the condenser is connected, through the impedances 26 and 21, across the lines leading from the chokes 23 and 24 to the points 23 and 32, respectively. From the points 53 and 54, the terminals of the condenser 25, balancing connections, as shown, are led to the points 23 and 3| from which the operating potential for the cathode tube is derived, as already stated.

In Figure 1, a small fractional end part of the resistance between 3l and 32 is brought out to a variable resistor 33 under the control of the operator. By this device I am able to equalize the wave-lengths of a curve comprising several wavelengths, as shown by the oscillograph and to avoid distortion. Without such a convenient equalizing device, I have found that due to improper bias on the amplifier tube, distortion resulted, as shown by lack of equality in succeeding halfwaves displayed by the oscillograph. 'Ihe equalizing resistance 33, by controlling the potential of the point 3i with respect to the point 34, makes it possible to apply the proper biasing voltage to the grid 41 with respect to the filament 48. This enables the operator to control this bias and to eliminate distortion, so that successive waves are equal, as is necessary for correct observation.

When only a single quantity is under observation, as for example an electromotive force connected to the source A through the transformer a, the terminals of the secondary of-the transformermay be lconnected continuously to the deflecting plates I4 anc1 I4 a, respectively. 'I'he stabilizing circuit derives current, through the transformer a', as already explained, either directly or indirectly from the same source of periodic current.

A When two quantities are to be simultaneously observed, for example, an electromotive force from the source A and from the source B, these are successively applied to the deilecting plates by means of a rapidly moving polycyclic distributor, diagrammatically shown in Figure 5. In this figure, which, as has been stated, shows the development of one form of polycyclic distributor which I have used, I have indicated at 55 a brush which is connected to one of the deilecting plates, such as the plate I4 in Figure 1 and bears on a continuous motor-driven slip-ring 56, to which are connected staggered quadrants 51, 56, 59 and 60. respectively. A brush 6I bears on the quadrant 51 and is connected to the terminal 62 through a suitable resistance 63. A brush 64, bearing on the quadrant 56, is connected to the terminal 65, and the brushes 66 and 61, which bear on the respective quadrants 59 and GII are connected respectively to the terminals 68 and 69 each of the brushes being in series with a resistance similar to 63, these resistances being shown at 10, 1I and 12, respectively. The opposite terminal of each of the several circuits which is shown at 13 is connected to the deflecting plate I4. By this arrangement, the simultaneous observation of a number or varying quantities may be made, since, through the medium of the distributor, several currents or electromotive forces are applied to the deflecting elements separately in rapid succession.

A direct connection, as, for instance, from the terminal 62 to the terminal 13, give zero difference of potential between thedeilecting plates I4 and I4 and hence produces a zero line on the screen.

The distributor is driven, preferably, by a nonsynchronous motor, so that successive interruptions in the record of one wave do not occur at the same point in the cycle. It is understood that the distributor is driven at such a speed that, due to persistence of vision, the several waves produced on the screen separately in rapid succession, appear to be simultaneous and continuous.

Whereas it is preferable to use the resistor system as explained in connection with the embodiment of my invention, as shown in Figure 1, that part of my invention that relates to the electrical stabilization of the linear time-axis for a cathode-ray oscillograph may be applied independent of such resistor system. Such an application is shown in Figure 4. Here an independent battery 14, connected to the anode I3 and the cathode 6', is employed to supply the operating potential for the cathode-ray oscillograph tube. Batteries 15 and 16 are interposed between the points 32 and 3|' corresponding to the points 32 and 3| in Figure 1 and between 3| and corresponding to the ypoints 3| and 30 in Figure 1 to supply the proper electromotive force for the oscillating circuit 32', 34 and 30', the relative values of 15 and 16 being such that the point 3l is maintained at the proper potential.

In the application of my invention shown in Figure 4, no amplier is used, the function performed by such amplier being useful, although not essential. In Figure 4 I have shown as .substituted for the resistance 38 a thermionlc rectifying tube, with a grid 1T, plate 18 and lament 19, heated by current from battery 83, controlled by a resistor 84. When such thermlonic tube is operated above saturation. a constant current passes through the tube, charging the gasdischarge lamp 35' and the condenser 39' at a constant rate and causing the potential between the terminals of the gas-discharge lamp to increase in proportion to time and thus to give the desired linear time-axis. In order to precisely synchronize the successive charge and discharge oi the gas-discharge lamp 35' and so to stabilize the linear time-axis'in the manner described in connection with Figure 1, I introduce into the oscillating circuit in which the gas-discharge lamp is located, through the insulating transformer 80, a small electromotive force connected directly or indirectly with the source A that supplies the circuit 8l-82 under observation.

In Figure 1, I have shown the plates I4 and I4a as each being connected to a movable distributor member, such as those shown at I4x and I4Y. This, it will be understood, is a diagrammatic showing to indicate that the operation may be carried on by shifting the connections of both plates. In Figure 3, I have indicated an arrangement in which the connection from the plate I 4B is shifted at |45', the other plate being connected at all times at i4z to the opposite terminals of the circuits under observation. An

' elaboration of this arrangement has already been described in connection with Figure 5.

I claim: A

1. In a device of the type described, a cathoderay tube, a plurality of sources of electromotive force, means for causing the projection of a cathode beam, a plate for receiving the beam, means for deiiecting the beam in one direction to extents proportional to the several electromotive forces, periodically and in rapid succession, means to deflect the beam i n another direction fixed with respect to the rst direction to an extent proportional to the time, whereby curves comprising several Wave lengths are indicated on the plate, and means for equalizing the wave lengths of each curve, thereby preventing distortion.

2. In a device of the type described, a cathoderay tube, a plurality of sources of electromotive force, means for causing the projection of a cathode beam, a plate for receiving the beam, means for deflecting the beam in one direction to extents proportional to the several electromotive forces, periodically and in rapid succession, means to deect the beam in another direction to an extent proportional to the time, whereby curves comprising several wave lengths are indicated y,

on the plate, means for equalizing the wave/ lengths of each curve, thereby preventing distortion', and means for centering the curves upon the plate.

3. In a device of the type described, a cathoderay tube, a plurality of sources of electromotive force, means for causing the projection of a cathode beam, a plate for receiving the beam, a plurality of sets of deilecting elements associated with the tube, means including a distributor for connecting eaph of said several sources of electromotive force with one of said sets of deflecting elements periodically and in rapid succession, and means for impressing an electromotiye force upon another of said sets of defiecting elements.

4. In a device of the type described, a cathoderay tube, means for projectng a cathode beam, a source of electromotive force, means for deflecting the cathode beam in one direction, means for defiecting the beamvin another direction, a resistor circuit, means for causing a unidirectional current to flow through said resistor circuit, an oscillating circuit connected with said resistor circuitand having a gas-discharge lamp therein, and means for synchronizing the discharge .of said gas-discharge lamp with said sourceof electromotive force.

5. In a device of the type described, a cathoderay tube, two sets of deilecting elements associated therewith, an image-receiving member, a plurality of sources of electromotive force, means for causing the projection of a cathode beam, means for impressing upon one set of said delecting elements electromotive forces from said sources periodically and in rapid succession, whereby the beam is successively deflected in one direction to extents proportional to the several electromotive forces, means for impressing upon the other set of deflecting elements an electromotive force to deilect the beam in another direction fixed with respect to the rst direction to an extent proportional to the time, and means for indicating on the image-receiving member the resulting curves.

6. Apparatus for producing stationary luminous wave-form traces of a periodic electrical quantity on the screen of a cathode-ray oscillograph by deflection of a focused cathode beam, comprising an oscillation generator having the characteristic that it falls into synchronous relation at a rational ratio with a periodic voltage introduced into a circuit of said oscillation generator,` means including said oscillation generator for periodically deflecting said cathode beam in one direction in proportion to time, at a frequency which is determined by the frequency of said oscillation generator, means for deecting said beam in another direction in proportion to said periodic quantity, and a coupling between said oscillation generator and the source of said periodic quantity for introducing into said circuit of said oscillation generator a periodic voltage derived from the source of said periodic quantity to lock the frequency of said oscillation generator in synchronous relation at a rational ratio with the frequency of said periodic quantity, whereby the traces formed by said deflected cathode beam appear stationary.

'7. In apparatus for producing stationary luminous wave-form traces o-f a periodic electrical quantity on the screen of a cathode-ray oscillograph by deflection of a focused cathode beam, the combination of means including a gas-discharge tube oscillation generator adapted to generate a voltage of saw-tooth wave-form for periodically deflecting said beam in one direction at a frequency which is determined by the frequency of said oscillation generator, means for deflecting said beam in another direction in proportion to said periodic quantity, and means for introducing into a circuit of said oscillation generator in series with the discharge path of said gas-discharge tube a periodic voltage derived from the source of said periodic quantity to synchronize said oscillation generator precisely at a frequency which bears a rational ratio to the frequency of said periodic quantity, whereby the traces formed by said deflected cathode beam appear stationary.

8. In apparatus for producing stationary luminous wave-form traces of a periodic electrical quantity on the screen of a cathode-ray oscillograph by deflection of a focused cathode beam, the combination of an oscillation generator which tends to oscillate by itself at a frequency which bears approximately a rational ratio to the frequency of .said periodic quantity and having thel characteristic that it readily falls into synchronous relation with a small periodic voltage introduced into a circuit of said oscillation generator, the frequency of which voltage bears approximately a rational ratio to the frequency at which said oscillation generator tends to oscillate by itself, means including said oscillation generator for periodicaly deilecting said cathode beam in one direction in proportion to time, at a frequency which is determined by the frequency of said oscillation generator, means for defiecting said beam in another direction in proportion to said periodic quantity, and means for introducing into said circuit of said oscillation generator a small periodic Voltage derived from the source of said periodic Iquantity to synchronize said oscillation generator precisely at a frequency which bears a rational ratio to the frequency of said periodic quantity, whereby the traces formed by said deflected cathode beam appear stationary.

9. Apparatus for producing a plurality of stationary luminous traces on the screen of a cathode-ray oscillograph having horizontal and vertical deilecting elements for defiecting a focused cathode beam, said luminous traces being representations respectively, of the wave-forms of several periodic electrical quantities rationally related in frequency, which comprises in combination an oscillation generator having the characteristic that it falls into synchronous relation with a periodic voltage introduced into a circuit of said oscillation generator, means for impressing a voltage derived from said oscillation generator on said horizontal deflecting elements, a distributor for impressing voltages of said periodic quantities singly and in rapid succession on said vertical deecting elements, and means for introducing into said circuit of said oscillation generator a periodic voltage derived from-I the source of one of said periodic quantities to synchronize said oscillation generator precisely at a frequency which bears a rational ratio to the frequency of said last named periodic quantity, whereby the traces formed by said deflected cathode beam appear stationary.

10, In apparatus for producing stationary luminous wave-form traces of a periodic electrical quantity on the screen of a cathode-ray oscillograph by deflection of a focused cathode beam, the combination of an oscillation generator having the characteristic that it falls into synchronous relation with a periodic voltage introduced into a circuit of said oscillation generator, manual means for adjusting said oscillation generator to a frequency which bears approximately a rational ratio to the frequency of said periodic quantity, means including said oscillation generator for periodically deflecting said cathode beam in one direction at a frequency which is determined by the frequency of said oscillation generator, means for defiecting said beam in another direction in proportion to said periodic quantity, and means for introducing into said circuit of said oscillation generator a periodic voltage derived from the source of said periodic quantity to synchronize said oscillation generator precisely at a frequency Which bears a rational ratio to the frequency of said periodic quantity, whereby the vtraces formed by said deflected cathode beam appear stationary.

11. In apparatus for producing stationary luminous wave-form traces of a periodic electrical quantity on the screen of a cathode-ray oscillograph by deflection of a focused cathode beam, the combination of an oscillation generator having the characteristic that it readily falls into synchronous relation with a small periodic voltage introduced into a circuit of said oscillation generator, the frequency of which Voltage bears approximately a rational ratio to the frequency at which said oscillation generator tends to oscillate by itself, manual means for adjusting said oscillation generator to a frequency which bears approximately a rational ratio to the frequency of said periodic quantity, means including said oscillation generator for periodically deflecting said cathode beam in one direction at a frequency which is determined by the frequency of said oscillation generator, means for deecting said beam in another direction in proportion to said periodic quantity, means for deriving from the source of said periodic quantity a small periodic voltage, manual means for adjusting the magnitude of said small periodic voltage and means for introducing the adjusted periodic voltage into the said circuit of said oscillation generator to synchronize said oscillation generator precise y at a frequency which bears a rational ratio to the frequency of said periodic quantity, whereby the traces formed by said deflected cathode beam appear stationary.

12. In apparatus for producing stationary 1uminous Wave-form traces of a periodic electrical quantity on the screen of' a cathode-ray oscillograph by deflection of a focused cathode beam, the combination of an oscillation-generator circuit including a source of direct-current, a resistance, a capacity and a gas-discharge tube, said circuit constituting an oscillation generator adapted to generate a voltage of saw-tooth waveform, means for producing horizontal deflection of said beam at a frequency which is determined by the frequency of said oscillation-generator, means for producting vertical deflection of said said beam in proportion to said periodic quantity, and means for introducing into a. circuit of said oscillation-generator in series with the discharge path of said gas-discharge tube a small periodic voltage derived from the source of said periodic quantity to lock the frequency of said oscillation generator in synchronous relation With the frequency of said periodic quantity, whereby the traces formed by said deflected cathode beam appear stationary.

13. Apparatus for producing stationary luminous wave-form traces of a periodic electrical quantity on the screen of a cathode-ray oscillograph by deflection of a focused cathode beam, comprising a gas-discharge device, means including a source of direct current, a resistance and a condenser for causing periodic discharges of said gas-discharge device, means for deflecting said cathode beam in one direction at a frequency determined by said discharges, means for deflecting said beam in another direction in proportion to said periodic quantity, and means for applying a voltage derived from said quantity to said gas-discharge device, whereby the frequency of said discharges is caused to bear a rational ratio to the frequency of said quantity, and the traces formed by said deflected cathode beam appear stationary.

FREDERICK BEDELL.

DISCLAIMER Re. 20,945.-Fraderfick Bede, Ithaca., N. Y. DEVICE ron INDIGMING Osanna- GRAPB C Unvs s STATIONARY. Patent dated December 13, 1938. Disclaimer filed November 20, 1939, by the assignee, General Radio Company. Hereb enters this disclaimer bo claims I, 2, 3, and 5 in said speccation.

{(gcal Gazette December 12, 1989.) 

